Prostatic cancer has been estimated to affect as many as one in three men. In the U.S. alone, this implies an estimated fifty-million patients who are candidates for treatment of prostatic cancer. Prior methods of treatment include surgical intervention, external radiotherapy, and brachytherapy (interstitial radiation). A general discussion of the localized use of radiation therapy is found in Bagshaw, M. A., Kaplan, I. D. and Cox, R. C., Radiation Therapy for Localized Disease, CANCER 71:939-952, 1993. Disadvantages associated with surgical intervention include impotence and incontinence. External radiotherapy may have deleterious effects on surrounding normal tissues (e.g., the bladder, the rectum, and the urethra). In contrast, brachytherapy diminishes complications such as impotence and incontinence, and allows a higher and more concentrated radiation dose to be delivered to the prostate gland as compared to external radiotherapy. An additional advantage of brachytherapy is that treatment can be accomplished within a matter of days as compared to weeks, greatly reducing radiation exposure of the adjacent organs.
Prostate brachytherapy can be divided based upon the radiation level used into temporary implantation, which uses high activity sources, and permanent implantation, which uses lower activity sources. These techniques are described in Porter, A. T. and Forman, J. D., Prostate Brachytherapy, CANCER 71:953-958, 1993. The predominant radioactive sources used in prostate brachytherapy include iodine-125, palladium-103, gold-198, ytterbium-169, and iridium-192. Prostate brachytherapy can also be categorized based upon the method by which the radioactive material is introduced into the prostate. For example, an open or closed procedure can be performed via a suprapubic or a perineal retropubic approach.